In the production of entertainment media, such as motion pictures or music recordings, it is often necessary to coordinate schedules and budgets so that key persons are available to work together in a single studio location. Often, this coordination is difficult or impossible, sometimes requiring multiple production sessions to accommodate the schedules of producers, directors, performing talent, and technical personnel.
In order to accommodate these scheduling issues, and to reduce the costs associated with bringing all key persons to a single studio location, some studios have begun to experiment with remote collaboration. The idea of remote collaboration is to have each key person work at a local studio and communicate the results of their work from one location to another using a combination of digital and microwave technologies. The current state of these technologies can allow a recording to be made at one location and directly transmitted to another location for mixing or editing, with virtually no loss in audio quality during the transmission. Alternatively, the live audio can be electronically transmitted from one location for recording, mixing, or editing at another location, thus allowing remote collaboration between locations having a range of recording or production capabilities.
For example, announcers and other voice talent have used satellite links and telephone lines to record their lines for advertising agencies and television stations. Rather than paying to fly an announcer from Los Angeles to New York for a few hours work on an automobile commercial that is due in 24 hours, a New York ad agency books time at a local New York recording studio. The local studio, in turn, schedules satellite time and books a sending studio in Los Angeles where the announcer can record his or her lines. The announcer arrives at the Los Angeles studio while the producer of the commercial goes to the New York studio. The latest script is sent by facsimile to Los Angeles minutes before the recording session begins. The studios patch the recording from Los Angeles to New York using a high quality satellite audio link, while the producer makes his comments over an ordinary long-distance telephone line. An hour or so later, the recording for the commercial is complete.
Another example of remote collaboration relates to music overdubs. Using the above dual studio scenario, a record producer can direct the mixing, mastering, or overdubbing of a music recording from one studio, using recording equipment located at another studio. Again,. the process is more efficient and can save substantial time, travel, hotel, per diem costs, etc.
The above examples illustrate that considerable savings can be realized using remote collaboration. However, the current approach to remote collaboration has an important limitation. Although the use of telecommunications technology can dramatically improve the efficiency of communications between studio locations, each studio continues to operate asynchronously to the others, with little or no real time coordination among them. Thus, while portions of a recording or other media can be transmitted between studio locations, mixing and editing these portions to form a final product must occur at a single studio location. This requirement derives from the need to precisely synchronize the portions to each other.
For example, in the production of motion pictures, the picture and soundtrack are usually produced separately at different studio locations using physically separate equipment and media. However, the design and composition of the soundtrack is based upon the action and aesthetic requirements of the picture. Thus, when the picture and soundtrack are brought together during audio post-production, a method and apparatus is needed to synchronize the film projector with the audio recorder/player. Without precise synchronization, the picture and soundtrack will quickly wander; the soundtrack will not closely follow the picture making it virtually impossible for the producer to complete the post-production edits.
A common method for synchronizing a motion picture with a soundtrack is to use electronic audio-image synchronization signals. The audio-image synchronization signals typically employed during motion picture post-production are generated by the film projector or audio recorder/player. The equipment that generates the audio-image synchronization signal uses it to control and synchronize the other equipment in the system. For example, a synchronization signal which is generated by the film projector may be used to control the playback speed and direction of the audio recorder/player. Similarly, the audio recorder/player can generate a synchronization signal which may be used to control the speed of the film projector. Moreover, the audio and video equipment is installed in a single sound studio which allows the equipment to be easily interconnected in order to maintain the required synchronization.
A typical audio-image synchronization signal used widely in the motion picture industry is called a "Bi-Phase" signal, and consists of two signal channels labeled "phase A" and "phase B". Each channel of the Bi-Phase signal contains an analog squarewave signal that is modulated in frequency over a continuous range of 0 to approzimately 960 Hertz. The modulation frequency of the Bi-Phase signal represents the rotational speed of the audio recorder, with 240 Hertz representing normal play speed. In addition, the phase difference between phase A and phase B signals indicates the rotational direction of the audio recorder/player. For example, clockwise rotation is indicated by the phase A signal leading the phase B signal by 90 degrees, while counter-clockwise rotation is indicated by the phase A signal lagging the phase B signal by 90 degrees.
During post-production of the soundtrack, the producer of the film views the motion picture and listens to the soundtrack simultaneously, while giving editing instructions to the artistic and technical crews. Typically, the producer conducts post-production at the sound studio where the soundtrack was produced, in order to make the immediate editing decisions needed to enable the artistic and technical crews to efficiently complete post-production of the soundtrack. Unfortunately, the post-production process often requires several editing sessions spread over different times during the filmmaking process, and each session may last for several days. Therefore, a significant amount of traveling, rescheduling, and expense may be required for the producer to manage the post-production at the sound studio.
A solution to the above problem is for the producer to apply remote collaboration; to view the motion picture at a receiving studio while simultaneously listening to and controlling the soundtrack which is being played and transmitted from a remote sending studio. This approach requires both the soundtrack and synchronization signals to be simultaneously communicated between the studios using a digital telecommunications network. However, since the Bi-Phase signal is analog, it is not compatible with these networks. If the Bi-Phase signal could be properly formatted, it could then be sent over existing digital telecommunications networks, thus allowing equipment at the receiving studio to be properly synchronized with equipment at the sending studio.